Order of titles

ABSTRACT

A method of recording an encoded bit stream that represents video objects includes recording a collection of contiguously arranged video objects and management information about recorded video objects. The collection is partitioned into adjacent recordings that represent playable titles, where a playable title is defined as a playback sequence of all complete cells or a subset of complete cells of a recording in the order of allocation within the video object storage area on the disc. The method further includes generating a title list of titles sorted in the order of arrangement within the video object area on the disc. The method further includes defining a free space title that represents free space within the video object area and includes the free space title in the title list.

FIELD OF THE INVENTION

The invention relates to a method for recording encoded informationsignals on a disc like record carrier, such as an optically readabledisc. The invention further relates to a recording apparatus forperforming the method.

BACKGROUND OF THE INVENTION

The DVD-Video format for optically readable discs is defined in the DVDSpecifications for Read-Only Disc, part 3: Video Specifications (version1.0, August 1996). Relevant parts therefrom are being disclosed in forinstance European Patent Application EP 724 264 and U.S. Pat. No.5,784,528, respectively document D1 and D2 in the list of referreddocuments that can be found at the end of this description. Bothdocuments are incorporated by reference herein.

The DVD-Video format as defined in the above mentioned Specifiations forREAD-Only Disc and disclosed in D1 and D2 was created for storing moviesand other video content on read-only DVD media. Some of the features ofthe DVD-Video format make it less suitable for real-time recordingapplications.

However, it is desirable to create and record video streams andassociated data structures on rewritable media in real time which areshould preferably be almost identical to the structures defined in theDVD-Video format. Such rewritable discs should be play back compatiblewith the majority of the installed base of consumer DVD-Video players.The method according to the invention describes a novel and inventiveformat for DVD-Video compatible real-time recording of video streams,referred to hereinafter to as Real Time DVD Video Recording or shortlyDVD-Video Recording. The format defined is intended for home videorecording on an optical medium which is playback compatible withDVD-Video players.

The above-mentioned DVD-Video format demands that data for a VTS beallocated contiguously. This gives all kinds of problems when part ofthe data is overwritten with new recordings:

The DVD-Video format allows an arbitrary numbering of Video Titles (VT)within a Video Title Set (VTS). For instance such as the sequence ofVideo Titles: VT1, VT3, VT2 . . . . Overwriting for instance Video TitleVT 3 with a new and larger Video Title VT4, will result in overwritingalso Video Title VT2. This would appear strange to a user, employing aVideo Title menu listing the Video Titles in consecutive order: VT1,VT2, VT3, . . . . Such a sequence would be changed into a sequence like:VT1, X, VT4, . . . with X denoting a deleted Video Title.

Thus, when partial overwrite is one of the features, the user model ofthe recording medium becomes complicated.

OBJECT A/VD SUMMARY OF THE INVENTION

In consequence, amongst other things, it is an object of the inventionto obviate the above-mentioned disadvantages.

By defining the playable items and the list of playable titles in theorder of allocation, the recording medium appears to a user as asequential, tape like medium. The user will understand that whenoverwriting a specific recording, a subsequent recording may beoverwritten too. He would not understand this if the recordings wererandomly ordered, as allowed in the DVD Video format, possibly leadingto disappearing of a previous recording when overwriting a specificrecording.

This allows a playback device to employ a simple user model in case ofreal time DVD video recordings. A title menu, used by a player fordisplay and selection, can simply be read from the management area.There is no need to read the information in the video storage areaitself and consequently calculating a title menu. This means that aplayer adapted for playback of pre-recorded DVD Read-Only discs, doesnot require modification in order to display a proper title menu.

BRIEF DESCRIPTION OF THE DRAWINGS

These and further aspects and advantages of the invention will beapparent from and elucidated in more detail hereinafter with referenceto the disclosure of preferred embodiments, in particular with referenceto the appended figures in which,

FIG. 1 illustrates the logical data structure of a DVD disccorresponding to an embodiment for DVD Video Recording according to theinvention;

FIG. 2 illustrates more in detail the structure of the Video Managerarea (VMG) of FIG. 1;

FIG. 3 illustrates more in detail the structure of the Video Title SetInformation area (VTSI) of FIG. 1;

FIG. 4 illustrates the structure of the Video Manager InformationManagement Table (VTSI_MAT) of FIG. 2;

FIG. 5 illustrates the structure of the Program Chain Information area(PGCI);

FIG. 6 shows an example of finding a Titles Program Chain Information(PGCI);

FIG. 7 shows a recording apparatus according to a first embodiment ofthe invention, the respective units therefrom being illustrated in moredetail in the following figures of which

FIG. 8 shows an AV input unit;

FIG. 9 shows a CODEC unit;

FIG. 10 shows an A/V output unit;

FIG. 11 shows a drive unit, and

FIG. 12 shows a system control unit.

DESCRIPTION OF THE EMBODIMENTS

The data structure to be disclosed hereafter explains the DVD-Videocompatibility behind the Real-Time Video Recording Format and specifieshow it should be used by recorders to create DVD-Video playbackcompatible discs.

To overcome limitations for real-time recording of the DVD-Video formatfor read-only discs, a number of changes have been made to the dataorganization and the use of some of the recording parameters in thereal-time data stream.

The use of Titles and Menus is restricted to improve exchangeability ofrewritable discs between recorders. In addition to this, strict rulesare defined for Play Lists, which can be created by the user to defineplayback sequences of pieces from the recorded Titles.

First a list of definitions is given.

Access Unit

Coded representation of a presentation unit. See ISO/IEC 13818-1 relatedto MPEG-2 systems, document D3 in the list of referred documents thatcan be found at the end of this description, for a more detaileddefinition of MPEG audio and video access units.

Buffer Cell

Last Cell of a Video Object (VOB) containing just one Video Object Unit(VOBU). The Buffer Cell is not used by any Program Chain (PCGC). TheCell ID of a Buffer Cell is equal to 255.

Cell

Sequence of one or more Video Object Units (VOBU). The first VOBU of aCell shall contain video data. Cells are the basic presentation unitsfor the Program Chains (PGC)

Chapter

Subdivision of a Title. Other word for Part_of_Title (PTT).

DVD-VR Format

Short for Video Format Specifications for Real-Time DVD-Video Recording.

DVD-Video Format for Read-Only Discs

Format as specified in the DVD specifications for Read-Only Disc-Part 3:Video Specifications (version 1.0, August 1996), elements of which arebeing disclosed in D1 and D2.

DVD-Video Format for Rewritable Discs

Format of DVD-Video related structures with the modifications specifiedin this disclosure.

Elementary Stream

An elementary stream is a generic term for a sequence of coded video,coded audio, coded graphics or other access units that can be correctlydecoded by a hypothetical decoder operating without special control froman external controller.

Free Space

Recording which is represented by a Free Space Title in the Title SearchPointer Table. If the last Recording is free space, it is notrepresented in this table.

Free Space Title

Full Title or Play List Title which cannot be played back as the relatedProgram Chain Information contains a pre-command to prevent this.Time_Play( ), Time_Search( ), PTT_Play( ) and PTT_Search( ) for a FreeSpace Title are blocked. The Cell information in the Program Chain of aFree Space Title may not be reliable.

Full Title

Title representing one Recording.

When a Full Title is played, all complete Cells (except the BufferCells) contained in the Recording are played in the order of dataallocation in the VTS Title VOBS. Full Titles may be accessible via theTitle Menu.

Group of Pictures (GOP)

Series of coded pictures starting with a GOP-header followed by an intracoded picture. The GOP represents up to 36 display fields at a rate of59.94 Hz, or 30 fields at a rate of 50 Hz.

MPEG-2 Program Stream (MPEG-2 PS)

Program Stream as defined in ISO/IEC 13818-1 related to MPEG-2 systems,document D3 in the list of referred documents that can be found at theend of this description.

Multiplexed Stream

A multiplexed stream is a single bit-stream, combining one or severalelementary streams that can be played in synchronism.

Play List (or Play List Title)

Title representing a play back sequence of Cells from one Recording.Play Lists are accessible via the Title Menu.

Program Chain (PGC)

Playback sequence of Cells for the presentation of a Menu or a Title.

Real Title

Full Title or Play List Title which is not a Free Space Title.

Recording

Contiguous piece of the VTS Title VOBS, enclosing an integer number ofMPEG-2 PS packs.

The VTS Title VOBS is partitioned into adjacent Recordings which do notnecessarily coincide with the VOBs in the VOBS.

Title

User accessible unit listed in the Title Search Pointer Table.

Title Menu

This is a menu that gives the user access to Play Lists and optionallyto Full Titles.

Title Search Pointer Table

Table in the Video Manager listing all available Play Lists and FullTitles on the disc. It is a starting point for finding the data that isrelevant for playing back a Title.

Video Manager (VMG)

DVD-Video data structures containing information about the recordedvideo data and the Title Menu. The Title Search Pointer Table is one ofthe elements of the Video Manager.

Video Object (VOB)

A Video Object is (a part of) a sequence of contiguously recorded Cells,together constituting (a part of) an MPEG-2 Program Stream.

An integer number of MPEG-2 Program Stream packs may be missing from thebeginning of the first Cell of the VOB, if this Cell is not used by anyTitle. The last Cell of a VOB is a Buffer Cell.

A VOB shall contain one video elementary stream. Gaps in the videostream are allowed under conditions specified by the DVD-Videospecifications.

According to the DVD-Video specifications a VOB may also contain up toeight Audio streams (in elementary audio streams and/or in privatestreams) and up to 32 Sub-picture streams. The DVD-VR format only allowsone Audio stream and one Sub-picture stream within the same VOB.

Video Object Unit (VOBU)

Integer number of MPEG-2 Program Stream packs representing apresentation period between 0.4 and 1.0 seconds.

The last VOBU of a Cell has a maximum presentation period of 1.2seconds. When the VOBU contains Video, the video data consists of aninteger number of GOPs and starts with a sequence header, a GOP headerand an intra coded picture.

A Sub-picture Unit is optional in a VOBU and cannot cross VOBUboundaries. The SPU's associated validity period ends at or before theend presentation time of the VOBU.

Video Object Set (VOBS)

This is a collection of contiguously recorded VOBs.

VOBs which are used for the menus are stored in the Video Manager VOBS(VMGM_VOBS). VOBs which are used for the Titles are stored in the VTSTitle VOBS (VTSTT_VOBS).

FIG. 1 shows the general data structure in accordance with the Real-TimeVideo Recording format. The data structure comprises a Lead-In area(LI), a Volume (VOL) and File System area (FS), a Video Manager area(VMG), one Video Title Set (VTS), an area reserved for other structures(OTHER) and a Lead-Out area (LO) as known from the DVD-ROM datastructure. Not specifically shown in FIG. 1 is Presentation ControlInformation (PCI) and Data Search Information (DSI) within the VideoObject Set for VTS Titles (VTSTT_VOBS), both dispersed in the NavigationPacks (NV_PCK) of each Video Object Unit (VOBU).

The data organization according to the Real-Time Video Recording formatwill first be discussed in general.

With respect to the Video Manager (VMG) the following is remarked. TheVideo Manager (VMG) shall contain a Title Menu. Consequently a VideoObject Set for Video Manager Menu (VMGM_VOBS) is mandatory.

With respect to the Video Title Sets (VTS) the following is remarked.The data structure on a disc contains only one Video Title Set (VTS).The Root Menu shall contain a dummy Program Chain (PGC) with apre-command calling the Title Menu. No other Video Title Set (VTS) menusshall be present on the disc. Consequently the Video Title Set (VTS)does not contain a Video Object Set for a Video Title Set Menu(VTSM_VOBS). The Video Object Set for Video Title Set Titles(VTSTT_VOBS) of the Video Title Set (VTS) contains the recorded videocontent.

With respect to the Video Object Set (VOBS), the Video Objects (VOBs)and Cells, the following is remarked. A Video Object (VOB) is (a partof) a sequence of contiguously recorded Cells, together constituting (apart of) an MPEG-2 Program Stream as defined in D4. An integer number ofMPEG-2 Program Stream packs may be missing from the beginning of thefirst Cell of the Video Object (VOB), if this Cell is not used by anyTitle. The last Cell of a Video Object (VOB) is a Buffer Cell, which isnot used by any Title. A Video Object Set (VOBS) is a collection ofcontiguously recorded Video Objects (VOBs). Video Objects (VOBs) andCells on a rewritable disc are not fully compliant with the VideoSpecifications for the DVD Read-Only Disc as disclosed in D2 and D4. Thefollowing exceptions are allowed or required:

-   1) The DVD-Video specification demands that a Video Object (VOB)    starts with an System Clock Reference (SCR) equal to zero. This is    not required for DVD-VR discs.-   2) The Display of the video stream from one Video Object (VOB) does    not have to start with a top field nor have to end with a bottom    field.-   3) The DVD-Video specification prescribes incremental numbering of    Video Objects (VOBs) and Cells. When recording the disc for the    first time that requirement can generally be met. However, when old    recordings are (partly) overwritten, or when the user does editing,    it may not be possible to maintain the incremental numbering. To    overcome this problem, DVD-VR format requires that the Video Object    Identification number (VOB ID) of all Video Object (VOBs) is equal    to ‘1’. In addition to this, Cell ID numbers (except number 255)    remain unique but they are allowed to be non sequential.-   4) Video Objects (VOBs) and Cells contain Navigation packs (NV_PCK)    with forward references to facilitate forward search. Some of these    forward references cannot be known at recording time and therefore    must be encoded with values that make legacy playback devices behave    in an acceptable way.-   5) The Navigation packs (NV_PCK) also contain a parameter specifying    the presentation termination time of the last video frame of the    Video Object (VOB). This parameter cannot be made correct in real    time in all cases. To solve this problem a high number will be    recorded for this parameter. A Buffer Cell at the end of a Video    Object (VOB) guarantees that the end of a Video Object (VOB) is    never reached during play back.

With respect to recordings, the following is remarked:

The Video Object Set for Titles in a Video Title Set (VTSTT_VOBS) can bepartitioned into a collection of adjacent pieces, called Recordings,which do not necessarily coincide with the Video Objects (VOBs).Recordings enclose an integer number of MPEG-2 PS packs.

Recordings relate to the partitioning of the content as it is presentedto the user.

With respect to Full Titles, Play Lists and Free Space, the following isremarked:

For each Recording two One_Sequential_PGC_Titles are created: one FullTitle and one Play List. The Full Title defines play back of allcomplete Cells (except Buffer Cells) of a Recording in the order ofallocation in the Video Object Set (VOBS). The Play List may bedifferent from the Full Title. If so it defines play back of a subset ofthe Cells which are played by the Full Title.

Full Titles and Play Lists are each represented as a Title in the TitleSearch Pointer Table in VMGI (TT_SRPT) and as a Title Unit (TTU) in thePart_of_Title Search Pointer Table in the VTSI (VTS_PTT_SRPT). A PlayList points to the same Program Chain (PGC) as the corresponding FullTitle, unless a different Program Chain (PGC) is recorded for the PlayList.

Full Titles and Play List Titles are Real Titles, unless they are taggedas Free Space. When a Full Title is deleted by the user, both the FullTitle and the Play List in theTitle Search Pointer Table (TT_SRPT) aretagged as Free Space by setting a unique Playback Type value (TT_PB_TY).If two consecutive Full Titles are deleted, the entries in the TitleSearch Pointer Table (TT_SRPT) shall be combined into one new Title.Also the related Play Lists are combined and tagged as Free Space. Freespace that is available on the disc at the end of the VTS Title VOBS orbeyond the boundaries of the VTS, is not reflected in the TT_SRPT. FIG.6 illustrates an example of finding a Title's PGCI.

Within FIG. 6 the following data structures are given: Title Play BackType (TT_PB-TY), Number of Part_of Title (PTT_Ns), VTS Title Number(VTS_TTN), PGC_Number (PGCN), Program Number (PGN), Start Address of VTSProgram Chain Information Table (VTS_PGCI-SA), Program Chain InformationTable (PGCIT), Number of Angles (AGL-Ns), Parent_ID_field for Title(TT_PTL_ID-FLD), VTS Number (VTSN) and Parent ID-field (PTL_ID_FLD).

Each Title (except for the last Play List Title and the last Full Title)is linked to the next Title by a LinkPGCN instruction in the associatedProgram Chain Information (PGCI). The Program Chain Information (PGCI)of the last Play List and the last Full Title contains a CallSS to theTitle Menu. If the Title is tagged as Free Space, this instruction isstored as a pre-command in the Program Chain Information (PGCI).Otherwise the instruction is stored as a post-command.

The number of Full Titles on a DVD-VR disc is equal to the number ofPlay Lists with a maximum of 49. Titles can be sub-divided into amaximum of 99 Chapters (Part_of_Titles). The maximum number of Chaptersfor all Full Titles on one disc is 254.

In the following the restrictions and modifications compared to theread-only format will be given.

As already disclosed with reference to FIG. 1, exactly one Video TitleSet is recorded on disc. FIG. 2 illustrates the data structure of VideoManager General Information (VMGI) within the Video Manager (VMG) areaas shown in FIG. 1. As in FIG. 1, the Presentation Control Information(PCI) and Data Search Information (DSI) are not shown in FIG. 2,although this information is dispersed in corresponding Navigation Packs(NV_PCK) in each Video Object Unit (VOBU) of the Video Object Set forthe Video Manager Menu (VMGM_VOBS).

With respect to the Video Manager Information Management Table(VMGI_MAT), the first 8 bytes of the Provider Unique ID (PVR_ID)contains the string ‘DVD-VR01’. The First Play Program Chain (FP_PGC)contains just a JumpSS to the Title Menu as a pre-command.

The Title Search Pointer Table (TT_SRPT) consists of two sections ofequal length. The first half contains pointers for N Play Lists and thesecond half contains pointers to N Full Titles. Play Lists as well asFull Titles are sorted in the order of incrementing start addresses ofthe first used Cell in the Video Object Set (VOBS). All Titles areOne_Sequential_PGC_Titles for which Time_Play( ) and Time_Search( ) areblocked. Part_of_Title_Play( ) and Part_of_Title Search( ) shall beblocked for Titles which are associated with Free Space and shall not beblocked for other Titles. Table 1 lists allowed Playback Types asindicated by the Title_Playback_Type (TT_PB_TY) field.

TABLE 1 Allowed values of TT_PB_TY Value of TT_PB_TY Type of Title 00000101b Real Title which is not the last Play List or not the last FullTitle 0001 0101b Real Title which is the last Play List or the last FullTitle 0000 0111b Free Space Title

The Video Manager Menu Program Chain Information Unit Table(VMGM_PGCI_UT) is just linked to the Title Menu. There shall be only oneLanguage Unit. The Video Manager Menu exists in this Language Unit.

Following the Video Title Set Attribute Table (VTS_ATRT), the VideoManager Menu Cell Address Table (VMGM_C_ADT) is restricted to a maximumof 170 cells and the Video Manager Menu Video Object Unit Address Map(VMGM_VOBU_ADMAP) to a maximum of 511 VOBUs. The remaining part of theVideo Manager area (VMG) is occupied with the Video Manager Menu VideoObject Set (VMGM_VOBS) and the back up of the Video Manager Information(VMGI_BUP).

With reference to FIG. 3, the Video Title Set Information (VTSI) will bediscussed. As the Root Menu contains just a dummy Program Chain (POC)and other menus are not allowed, the Video Title Set (VTS) Menus have noassociated Video Object (VOB) data. Consequently the Cell Address Tableof the Video Title Set Menu (VTSM_C_ADT) and the Address Map of theVideo Object Unit of the Video Title Set (VTSM_VOBU_ADMAP) do not exist.

The Management Table of the Video Title Set Information (VTSI_MAT)comprises the following area (not shown in the figure):

-   -   the VTS Video Attributes (VTS_V_ATR) (the video compression mode        complies with MPEG-2),    -   the number of Audio Streams (VTS_AST_Ns) describing the number        of different audio stream attribute sets used in this VTS,    -   the VTS Audio Stream Attribute Table (VTS_AST_ATRT) listing the        different audio stream attribute sets which are defined (and may        or may not be used) for this VTS. The PGCI for each Title        defines which of the sets is actually used,    -   the number of Sub-picture Streams (VTS_SPST_Ns) (set to one in        this VTS) and    -   the VTS Sub-picture Stream Attribute Table (VTS_SPST_ATRT) (all        fields in this table are zero)

The Video Title Set Information (VTSI) further comprises further a VideoTitle Set Part_of_Title Search Pointer Table (VTS_PTT_SRPT) wherein theTitle Units are recorded in the same order as Titles in Title SearchPointer (TT_SRPT).

Next is present a Video Title Set Program Chain Information Table(VTS_PGCIT). The number of Video Title Set Program Chain Information(VTS_PGCI) search pointers is equal to the number of Titles in TitleSearch Pointer Table (TT_SRPT). The search pointers are recorded in thesame order as the Titles. All Program Chains (PGCs) are Entry PGCs withall bits zero for Block mode, Block type and Parental ID Field(PTL_ID_FLD). When a Play List is equal to the associated Full Title,their Start Address of Video Title Set Program Chain Information(VTS_PGCI_SA) values are identical.

With respect to the Video Title Set Menu Program Chain Information UnitTable (VTSM_PGCI_UT) the following is remarked. The number of VideoTitle Set Menu Language Units as specified in VTSM_PGCI_UTI shall be 1.There is exactly one Video Title Set Menu Language Unit Search Pointer(VTSM_LU_SRP). The Video Title Set Menu Existence field (VTSM_EXST)shall contain the value (1000 0000b) to indicate that just the Root Menuexists. The Video Title Set Menu Language Unit (VTSM_LU) contains justone Program Chain Information Search Pointer (VTSM_PGCI_SRP). The VideoTitle Set Menu Program Chain Category parameter (VTSM_PGC_CAT) for theVideo Title Set Menu Program Chain (VTSM_PGC) contains the value (83000000h) indicating that the associated Program Chain (PGC) is the EntryPGC for the Root Menu. There is exactly one Video Title Set Menu ProgramChain Information (VTSM_PGCI).

The Video Title Set Time Map Table (VTS_TMAPT) contains Video Title SetTime Maps (VTS_TMAPs) that are present for all Titles on the disc but donot contain any map entries.

With respect the Video Title Set Cell Address Table (VTS_C_ADT), theparameter containing the number of Video Object in the Video Title Set(VTS_VOB_Ns) contains the contains the value ‘1’. It is noted that theVTS_VOB_Ns does not reflect the actual number of VOBs in the VideoObject Set of a rewritable disc. It is set to 1 as the VOB ID number ofall VOBs is set to ‘1’. All Video Title Set Cell Piece Information(VTS_CPI) have the same value (‘1’) for the Video Title Set Video ObjectID Number (VTS_VOB_IDN). Exactly 254 VTS_CPI blocks are recorded withVTS_C_IDN starting from ‘1’ and incrementing up to and including ‘254’.The Start Address and End Address of the Video Title Set Cell Piece(VTS_CP_SA and VTS_CP_EA) of Cell Pieces which are not referenced by anyPGC of a Real Title contain the value (0000 0000h). It is noted thatCell Pieces that are referenced by a PGC of a Free Space Title containzero start and end addresses.

With respect to The Video Title Set Video Object Unit Address Map(VTS_VOBU_ADMAP) it is remarked that all Video Object Unit (VOBU) startaddresses of the VOBUs which are completely contained in VTSTT_VOBS arelisted here in ascending order. It is noted that VOBU start addresses ofVOBUs which are part of Free Space are also included in the VTS VOBUAddress Map.

Next the structure of the Program Chain Information area (PGCI) forTitle Program Chains will be given with reference to FIG. 5. Thisstructure comprises a Program Chain General Information Area (PGC-GI), aProgram Chain Command Table (PGC_CMDT), a Cell Playback InformationTable (C_PBIT) and a Cell Position Information Table (C_POSIT).

With respect to the Program Chain General Information (PGC-GI) it isnoted that exactly one of the Availability flags in the Program ChainAudio Stream Control Table (PGC_AST_CTLT) is set to (1b). When thei^(th) Availability flag is set, the i^(th) Audio stream parameter setdefined for this Video Title Set (VTS) is valid for this Program Chain(PGC). The Decoding Audio stream number is always ‘0’.

The availability flag of the first Program Chain Sub-picture StreamControl (PGC_SPST_CTL) field in the Program Sub-picture Stream ControlTable (PGC_SPST_CTLT) is set to (1b). All other bits of the ProgramSub-picture Stream Control Table (PGC_SPST_CTLT) contain the value (0b).

The Program (PG) Playback mode in the Program Chain Navigation Control(PGC_NV_CTL) is set to sequential playback. The Still time value is setto no Still.

The PGC Command Table (PGC-CMDT) contains exactly three commands.According to this version of the specification only one command isactually used (for Title linking), the other two commands are NOPcommands (0000 0000h). Which command is used for Title linking isdefined in Table 2.

TABLE 2 Commands in PGCI PGC associated with . . . contains . . . as a .. . Real Title which is not the LinkPGCN post-command last Play List ornot the last to PGC of next Real Title Full Title in TT_SRPT Real Titlewhich is the last CallSS post-command Play List or the last Full Titleto Title Menu in TT_SRPT Free Space Title LinkPGCN pre-command to PGC ofnext Real Title

With respect to Cell Playback Information Table (C_PBIT): Cells are notpart of an Angle Block and do not exist in an Interleaved Block.

With respect to the Cell Position Information Table (C_POSIT): theIdentification Numbers of the Video Objects of all Cells in the PGCcontain the value ‘1’. It is noted that, on DVD-VR discs, all VOBs havethe same VOB_IDN.

It is allowed that the Cell ID number of a Cell of which the Seamlessplayback flag set in Cell Playback Information, is not the same as theprevious Cell ID number incremented by 1.

With respect to the Presentation Control Information (PCI) it is notedthat modifying a Play List may require that a Cell is split into two newCells. In that case all values of Cell Elapse Time (C_ELTM in PCI_GI)shall be updated in all PCI fields in the second Cell.

Additional data fields with respect to the DVD-Video format forRead-Only discs for carrying real-time stream attributes are givenbelow.

The last reserved 32 bytes of the General Information of PresentationControl In formation (PCI_GI) are redefined in t his specification asshown in table 3

TABLE 3 Redefinition of reserved fields at end of PCI_GI Number ofContents bytes Reserved Reserved 16 bytes (8) PCI_GI_XI PCI_GI ExtensionInformation 1 byte (9) RT_V_ATR Video Attributes 1 byte (10) RT_AST_ATRAudio Stream Attributes 1 byte Reserved Reserved 13 bytes Total 32 bytes

PCI_GI_XI identifies the application and specifies the length of theextension. If all bits in this byte are zero, also the bytes of PCI_GIfollowing this field are zero:

Application Identifier contains the value (0001b) if the streamattributes as defined in VTSI_MAT for this VTS must be overruled by thereal-time stream attributes. Otherwise contains the value (0000b). Thereal-time stream attributes are valid from Start PTM until End PTM ofthe VOBU in which this field is contained.

Extension Length defines the number of bytes for this extensionfollowing this field. It shall contain the value (0010b) if ApplicationIdentifier is (0001b). It contains the value (0000b) if ApplicationIdentifier is (0000b).

RT_V_ATR describes the real-time Video stream attributes.

Aspect ratio, Source picture letterboxed and Film camera mode havemeanings as defined in the DVD specifications for the Read_Only Disc.

RS_AST_ATR describes the real-time Audio stream attributes:

Surround Type as defined in the DVD Specifications of the Read-OnlyDisc. With respect to Data Search Information (DSI) it is noted that allVOBs are allocated in Contiguous Blocks and there are no Angles.

With respect to the Data Search Information General Information (DSI_GI)it is remarked that the Video Object ID number (VOB ID) number isalways 1. Further there is no requirement that the Cell ID numbers aremonotonically increasing from 1 in the Video Object. The following rulesshall be applied for Cell ID:

Cell ID is identical in all VOBUs belonging to the same Cell

Cells which are used by Real Titles are uniquely identified by theirCell ID

It is noted that modifying a Play List may require that a Cell is splitinto two new Cells. In that case all values of Cell Elapse Time (C_ELTMin DSI_GI) shall be updated in all DSI fields in the second Cell.

With respect to Video Object, it is remarked that an integer number ofMPEG-2 Program Stream packs may be missing from the beginning of thefirst Cell of the VOB, if this Cell is not used by any Title. The lastCell of a VOB is a Buffer Cell.

t is noted that seamless connections between VOBs are excluded.

nly one Audio stream is allowed within a VOB. The Audio decoding streamnumber is ‘0’.

nly one Sub-picture stream is allowed within a VOB. The Sub-picturedecoding stream number is ‘0’. Data for a Sub-picture Unit (SPU) isfully contained in one VOBU. The SPU validity period shall not startbefore the Start PTM of the VOBU, nor shall it end later than the EndPTM of the VOBU.

The DVD-Video format for rewritable discs is not fully identical to theDVD-Video format for read-only discs. The differences are (1) in therules for data allocation and (2) in some details of the navigation datain the real-time data streams. The first kind of differences generallyhas no consequences for DVD-Video players. As a consequence of thesecond kind of differences in some cases trick mode behavior ofDVD-Video playback devices with rewritable discs may not be alwaysexactly the same as with prerecorded discs. Manufacturers can improvecompatibility between DVD-Video players and rewritable discs byfollowing the guidelines given in the next.

With respect to VOBS Structures; on rewritable DVD-Video discs somerules for the Video Object Set data structures are different from therules for read-only discs. DVD-Video players will play back rewritablediscs well when they are robust against:

-   -   non-sequential numbering of VOBs in the VTSTT_VOBS    -   non-sequential numbering of Cells within a VOB    -   the existence of remnants of partly overwritten Cells or other        unused data in between “active” Cells    -   modified rules for forward search pointers as defined next:

DVD-Video recorders are required to at least fill in correct forwardpointers FWDI(n) for n≦M. Forward pointers FWDI(n) with M<n≦N containthe last correct value. For n>N forward pointers point to the end of thecurrent Cell. The duration of a Cell on a rewritable disc is typically60 seconds.

This means that for forward search functionality DVD-Video players canstill rely on the FWDI pointers for the lower speeds (2×, 4×, 8×). Forhigher speeds, the player can still use the long distance FWDI pointersbut in this case they point to the end of the current Cell. If accuratefast search speeds are desired, the speed can be adjusted by picking upintermediate pictures (e.g. by applying a FWDI(6) pointer) or byadapting the display period of the pictures.

FIG. 7 shows a recording apparatus according to a first embodiment ofthe invention. The recording apparatus is composed of several units. Oneunit is the A/V input unit 1. The A/V input unit 1 receives image andsound signals at antenna input terminal 2 and an external sound/imageinput terminal 3. The antenna input terminal 2 is adapted to receivebroadcasted modulated A/V signals transmitted by either satellite,terrestrial or cable source. The external sound/image input terminal 3is adapted to receive a non modulated audio signal or a non-modulatedvideo signals generated directly by respectively an audio or a videosource.

FIG. 8 illustrates the A/V input unit 1 in more detail. A tuner 5, whichis connected to the antenna input terminal 2, demodulates the modulatedA/V antenna signals and outputs the demodulated signals to a suitableA/V demultiplexing unit 6 for separating audio signals from videosignals. An audio A/D converter unit 7 outputs a digital audio signal Aand a NTSC/PAL/SECAM decoding unit 8, comprising a video A/D converter,outputs a digital video signal V. These signals A and V are outputted toa encoding/decoding unit 9, which is illustrated in more detail in FIG.9. The encoding/decoding unit 9 compresses and encodes the signals A andV, respectively by an audio encoder 10 and a video encoder 111, convertsthem to a multiplexed and compressed stream conforming to VideoRecording specifications, employing a multiplexer 12. To this purposesthe audio encoder 10 and video encoder 11 are adapted to perform sourcecompression according to a specific standard for compression, such asfor example MPEG-2 for audio and video.

The compressed and multiplexed stream is submitted via a track buffer13, which absorbs rate fluctuations stemming from intermittent recordingand data reproduction from a disc, to a drive unit 14. The encoding/anddecoding unit 9 also expands a compressed stream read from a recordingmedium by the drive unit 14 and outputs separately an audio signal A anda video signal V to the A/V output unit 15. To this purpose, theencoding/decoding unit 9 comprises a suitable A/V decoder 16 fordecoding the compressed audio and video source signals.

The A/V output unit 15, which is illustrated in more detail in FIG. 10,comprises an audio D/A converter 17 for outputting sound signals to anexternal sound output terminal 18. The A/V output unit 15 furthercomprises a video encoder—D/A converter unit 19 for outputting videosignals to an external image output terminal 20.

FIG. 11 illustrates the drive unit 14 in more detail. This unit 14receives the compressed stream generated by the encoding/decoding unit9, and adds an error-correction code by a suitable error correctionprocessing unit 21 to the stream. Next a channel modulation/demodulationunit 22 converts the stream with error-correction code to channel bitsadapted for recording on a recording medium 23. In case of a DVD-discthe EFM+ modulation scheme is being applied. Recording and reading incase of a recording medium 23 of the optical type, is performed by alaser comprised in an optical head unit 25. A laser power control unit24 is controlling the laser. Reflected signals from the recording medium23 are being converted by an amplifier and waveform equalizer circuit 26into two-value signals. The resultant compressed stream is furtherdemodulated by the modulating/demodulation unit 22, error corrected bythe error correction processing unit 21 and outputted to theencoding/decoding unit 9 via track buffer 13.

A servo circuit 27, connected to the amplifier and waveform equalizercircuit 26, controls the positioning of the optical head unit 25relative to the recording medium 23 and the rotational velocity of therecording medium 23 by controlling rotational driving means 28.

A system control unit 29, shown in FIG. 12, controls each block andperform file control, control information management and track buffercontrol. To this purpose a system control processing unit 30 is providedthat is being connected to memory means 31 loaded with a suitableoperation system. Operator input means 32 and operator output means 33are connected to the memory means 31. The operator input means 32comprising for instance keying means and the operator output meanscomprising display means.

Although the invention has been described with reference to preferredembodiments thereof, it is to be understood that these are notlimitative examples. Thus, various modifications thereof may becomeapparent to those skilled in the art, without departing from the scopeof the invention, as defined by the claims. The invention can beimplemented by means of both hardware and software, and that several“means” may be represented by the same item of hardware. Further, theinvention lies in each and every novel feature or combination offeatures. It is also remarked that the word ‘comprising’ does notexclude the presence of other elements or steps than those listed in aclaim. Any reference signs do not limit the scope of the claims.

LIST OF REFERRED DOCUMENTS

-   (D1) European Patent Application EP 724 264-   (D2) U.S. Pat. No. 5,784,528-   (D3) ISO/IEC 13818-1: 1995 Information Technology—Generic Coding of    moving pictures and associated audio information: Part 1: Systems    (MPEG2-systems)

1. A method of recording an encoded bit stream on a record carrier, saidencoded bit stream representing a plurality of video objects comprisinga sequence of cells, said method comprising the acts of: recording acollection of contiguously arranged video objects in a video objectstorage area of said disc, recording management information in amanagement information area of said disc for storing information aboutrecorded video objects, wherein said collection is partitioned intoadjacent recordings that represent playable titles, defining a playabletitle as a playback sequence of all complete cells or a subset ofcomplete cells of a recording in the order of allocation within thevideo object storage area on the disc, generating a title list of titlessorted in the order of arrangement within the video object storage areaon the disc, defining a free space title that represents free space thatis available on the disc within the video object storage area andincluding the free space title in the title list and in the playabletitle, creating two titles for the recording, the two titles including afull title and a play list title, and tagging as free space both thefull title and the play list title when a full title is deleted.
 2. Themethod according to claim 1, further comprising the act of blocking freespace titles for playback.
 3. The method according to claim 2, furthercomprising the act of converting a deleted title to a free space title.4. The method according to claim 3, further comprising the act ofgenerating a title menu listing the titles in a same order as in a titletable for allowing user access to the titles.
 5. A recording apparatusfor recording an encoded bit stream on a record carrier, the encoded bitstream representing a plurality of video objects comprising a sequenceof cells, the recording apparatus comprises: recording means forrecording a collection of contiguously arranged video objects in a videoobject storage area of said disc and for recording managementinformation in a management information area of said disc for storinginformation about recorded video objects, wherein said collection ispartitioned into adjacent recordings that represent playable titles, andsystem control means adapted to define a playable title as a playbacksequence of all complete cells or a subset of complete cells of arecording in the order of allocation within the video object storagearea on the disc and to generate a title list of titles sorted in theorder of arrangement within the video object storage area on the disc,the system control means being further adapted to define a free spacetitle that represents free space that is available on the disc withinthe video object storage area and to include the free space title in thetitle list, to create two titles for the recording, the two titlesincluding a full title and a play list title, and to tag as free spaceboth the full title and the play list title when a full title isdeleted.
 6. The recording apparatus according to claim 5, wherein thesystem control means are adapted to block free space titles forplayback.
 7. The recording apparatus according to claim 6, wherein thesystem control means are adapted to convert a deleted title to a freespace title.
 8. The recording apparatus according to claim 7, whereinthe system control means are adapted to generate a title menu listingthe titles in the same order as in a title table for allowing useraccess to the titles and the recording means comprises output means fordisplaying the title menu.
 9. The method according to claim 1, whereinthe act of generating the title list of titles further comprises the actof generating titles for both the playback sequence of all completecells and the subset of complete cells.
 10. The method according toclaim 9, wherein the act of generating the title list of titles furthercomprises the acts of: deleting at least one of the playback sequence ofall complete cells and converting the deleted sequence into the freespace title; and wherein the free space title representing the deletedsequence includes the title for the subset of complete cells.
 11. Themethod according to claim 10, wherein the act of generating the titlelist of titles further comprises the acts of: deleting multiple ones ofthe playback sequence of all complete cells; and converting all of thedeleted ones of the playback sequences and the respective subsets ofcomplete cells into a single free space title.
 12. The recordingapparatus according to claim 5, wherein the system control means furthergenerate the title list of titles for both the playback sequence of allcomplete cells and the subset of complete cells.
 13. The recordingapparatus according to claim 12, wherein the system control meansdeletes at least one of the playback sequence of all complete cells andconverting the deleted sequence into the free space title, and whereinthe free space title representing a deleted sequence includes the titlefor the subset of complete cells.
 14. The recording apparatus accordingto claim 13, wherein the system control means deletes multiple ones ofthe playback sequence of all complete cells, and converts all of thedeleted ones of the playback sequences and the respective subsets ofcomplete cells into a single free space title.
 15. A recording apparatusfor recording an encoded bit stream on a disc, representing a pluralityof video objects comprising a sequence of cells, recording apparatuscomprising: a recorder capable of recording a collection of videoobjects in a video object storage area of said disc and for recordingmanagement information in a management information area of said disc forstoring information about recorded video objects, wherein saidcollection is partitioned into adjacent recordings that representplayable titles; and a controller adapted to define a playable title asa playback sequence of all complete cells or a subset of complete cellsof a recording in the order of allocation within the video objectstorage area on the disc and to generate a title list of titles sortedin the order of arrangement within the video object storage area on thedisc, wherein each of the playback sequence of all complete cells andeach of the subset of complete cells have their own title, wherein thecontroller is further adapted to define a free space title thatrepresents free space that is available on the disc within the videoobject storage area and to include the free space title in the titlelist, to create two titles for the recording, the two titles including afull title and a play list title, and to tag as free space both the fulltitle and the play list title when a full title is deleted.
 16. Therecording apparatus according to claim 15, wherein the controller isadapted to block free space titles for playback.
 17. The recordingapparatus according to claim 15, wherein the controller is adapted toconvert a deleted title to a free space title.
 18. The method of claim1, wherein the full title is different from the play list title, theplay list title defining play back of a subset of the cells which areincluded in the full title.
 19. The recording apparatus of claim 5,wherein the full title is different from the play list title, the playlist title defining play back of a subset of the cells which areincluded in the full title.
 20. The recording apparatus of claim 15,wherein the full title is different from the play list title, the playlist title defining play back of a subset of the cells which areincluded in the full title.
 21. The method of claim 1, furthercomprising the act of combining into one new title deleted consecutivefull titles.
 22. The recording apparatus of claim 5, wherein the systemcontrol means are further adapted to combine into one new title deletedconsecutive full titles.
 23. The recording apparatus of claim 15,wherein the controller is further adapted to combine into one new titledeleted consecutive full titles.